Run results for: Transform dict values: for vs fromEntries 2

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36

Browser: Chrome 125

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
For each	305014.3 Ops/sec
fromEntries()	245029.9 Ops/sec

Script Preparation code:

function getRandomInt(min, max) {
  return Math.floor(Math.random() * (max - min + 1)) + min;
}

function generateRandomArray(length) {
  return Array.from({ length }, () => getRandomInt(1, 1000)); // Random values, but values themselves don't matter
}

function generateRandomDict(numEntries, maxArrayLength) {
  const dict = {};
  
  for (let i = 0; i < numEntries; i++) {
    const key = `key${i + 1}`;
    const arrayLength = getRandomInt(1, maxArrayLength);
    dict[key] = generateRandomArray(arrayLength);
  }
  
  return dict;
}

// Configuration
const numEntries = getRandomInt(1, 99); // Less than 100 entries
const maxArrayLength = 99; // Each array has less than 100 elements

// Generate the dictionary
var randomDict = generateRandomDict(numEntries, maxArrayLength);

console.log(randomDict);

Tests:

For each
const transformedForEach = {}; for (const key of Object.keys(randomDict)) { const arr = randomDict[key]; transformedForEach[key] = arr.map((item) => item * 2); }
fromEntries()
const transformedFromEntries = Object.fromEntries( Object.entries(randomDict).map(([key, arr]) => [ key, arr.map((item) => item * 2), ]), );

Run results for: Transform dict values: for vs fromEntries 2

For each

fromEntries()